Carburetor for aircraft engines without compressors



Nov. 25, 1952 R. H. nssn-zn CARBURETOR FOR AIRCRAFT ENGINES WITHOUTCOMPRESSORS 3 Sheets-Sheet 1 Filed April 2, 1949 Iuwsyrae aowflfn sul BL001? Co-en, qaukd a 40:11am

Rr-rrs CARBURETOR FOR AIRCRAFT ENGINES WITHOUT COMERESSORS Filed April2, 1949 3Sheets-Sheet 2 Nov. 25, 1952 R. H. TISSIER CARBURETOR FORAIRCRAFT ENGINES WITHOUT COMPRESSORS Filed April 2, 1949 3 Sheets-Sheet3 Patented Nov. 25, 1952 CARBURETOR FOR AIRCRAFT ENGINES WITHOUTCOMPRESSORS Roger H. Tissier, Paris, France, assignor to SocieteNationale dEtude et de Construction de Moteurs dAviation, Paris, France,a French pany Application April 2, 1949, Serial No. 85,142

In France April 2, 1948 4 Claims.

The carburetors for aircraft engines without an air compressor shouldmeet certain requirements:

1. For the comparatively high air inlet pressures. (on take 01f, orrated engine running), that is near the atmospheric pressure at groundlevel, the air-gasoline mixture provided by the carb retor should berich.

2. For the cruising load, the pilot should be able to obtain either amixture giving an economical consumption, or, during a, temporary periodof strenuous working of the. engine (for instance during climbing) acomparatively rich mixture.

3-. Finally, it may be useful, chiefly in the case of engines withoutair compressor, to. be able to obtain the maximum power ofthe engine atany altitude, that is to pass from the economical mixture to the mixturecorresponding to the maximum power.

If the carburetor is provided for manual altimetrical correction, theserequirements may be achieved at the cost ofimposing an additional dutyon the pilot. Moreover, this may lead to overstrain of the engine incase-thepilot, lacking experience in handling the control, sets thelatter ina position corresponding to too weak a mixture.

If the carburetor is arranged for automatic a1- timetric correction, itis convenient to be able to use asupplementary manual control in orderto pass. from the economical mixture to the maximum power or climbingmixture.

lnotherwords, in an engine without air compressor, under otherwise equalconditions, the downstream pressure with respect to the butterfly. orthrottle-control depends on the altitude and on the pressure-loss duetothe butterfly position.

The present invention has for its object to provide an adjusting deviceto obtain automatically the resultant of boththese factors on thecarburetor mixture and which can be conveniently combined with a manualcorrecting means available to the pilot, thus providing a richnesssuitable toeach admission pressure, both at altitude and ,on the ground,without requiring anadmissionipressure diaphragm.

Thisdevice-comprises a linkbetween thethrottle-lever (or the butterfly)and the altimetrical adjusting; needle ,or valve; operated-by means ofthe altimetrical-control box.

Other objects and advantages of the. invention will. be; apparent duringthe course-of the following" description.

In the. accompanying drawing forming a, part of; this application andinwhich like numerals 2 are employed to designate like parts throughoutthe same,

Figures 1 to 3 are diagrammatic cross-sections of three embodiments ofthe invention which may be applied to every aircraft engine withoutcompressor, whatever its principle.

These embodiments permit automatic enrich ment for high admissionpressures at ground level, as well as for full-throttle running up tothe altitude corresponding to the admission pressure necessitatingenrichment. Moreover, they allow, for an operating condition other thanhigh admission pressure conditions, automatic operation either With aweak mixture or with a rich one.

In the drawings, for convenience, the butterfly or air throttle It] hasbeen separated from the carburetor whose choke tube or venture formingthe mixing space is in Illa, but obviously, the air throttle is locatedas usual either in front, or behind this venture. The engine is in M; itsucks air through the tube 2 and venture Illa. The atmospheric air is inA.

In the embodiment shown in Fig. 1 an emulsifier I receives the liquidfuel as usual from a constant level container, not shown, which isconnected to the emulsifier through a duct Ia. Said emulsifier receivesfurther air through a channel Ib originatin at I-c upstream with re'spect to the nozzle Illa, so that the pressure of said air is theatmospheric one.

The exit. Id of said-emulsifier being connected to ports Illb providedin therest-ricted zone of the venturi. Illa, the. suction generated insaid zone by the air stream is transmitted through said ports to thesaid exitof the emulsifier. Consequently air and fuel are sucked inthrough said emulsifier and form a primary mixture (emulsion) which isfinally admitted through ports I U into the air. flowing. through nozzleIlia.

Carburetors of this kind are well known. is also known to regulate therichness of the final mixture in nozzleI Ga in the followingmannerz.

A channel 9a communicating with port I'c'and channel Ibis connectedwith. the exit Id of the emulsifier through a calibrated. aperturecontrolled. by a needle-valve 4 controlled in its turn by a pressureresponsive box 5,- the outline of this needle 4 being adapted toralterthe area of flow section between the wall of the aperture or seat 3 andthe needle 4, according to theaa'ltitu'de'.

The, proposed improvement comprises the following arrangements:

The altimetrical adjusting: needle-valve 4' isprovided with acylindrical extension 6on which a sleeve 1 freely slides, itsdisplacement being controlled by a lever 8. The needle is hollow andpierced with ports 9, at a, convenient height, on its cylindricalportion and also with ports 9b under the seat 3. Thus, through the duct9a, through ports 9 whose sizes are predetermined during adjustment andthrough ports 9?), a connection is established between the air-channel 2and the exit of the emulsifier I, thus causing a drop in the suctionover the emulsifier, and hence, a leaning of the mixture.

According to its position, the sliding sleeve I covers or uncovers thecalibrated ports 9.

The control of the position of this sleeve 1 is effected automaticallyby the rotation of the butterfly H]. For this purpose, a cam H is keyedto the axle We of butterfly I0, in such a way as to turn at the sametime as that butterfly when the throttle-control is operated. On thiscam is applied a roller 12a carried at the end of a connecting rod l2hinged on lever B. This lever pivots about a fixed point 8a and issubmitted to the action of a spring so which applies permanently theroller iEa on the cam ii. The connecting rod i2 is guided on thebutterfly axle by means of a slot ifid which this axle crosses. In thedrawing, cam H as well as connecting rod [2 are shown inside thesuction-duct of the engine. In practice, these members are outside thisduct, cam H being keyed to an extension of the butterfly axle lilo.

The device described causes the sleeve 1 to move along the extension 6of the needle 4 when the butterfly or throttle-control is operated, theposition of sleeve 1 depending therefore on that of the butterfly.

During operation at ground level and starting with a certain opening ofthe butterfly ii), the sliding sleeve 1 closes ports 9 of the adjustingneedle 6; the maximum richness is achieved when the ports are entirelyclosed (the butterfly is wide open).

If it is now assumed that the aircraft takes off with the butterfly wideopen, then as the aircraft climbs, the altimetrical-control diaphragmlengthens and causes the ports 9 to be uncovered, thus loweringprogressively the richness while the inlet pressure decreases.

Thus, at ground level and at altitudes, a mixture proportional to theinlet pressure is achieved.

Moreover by acting on lever 8 through a manual control, not shown,connected to the end 81) of lever B, it is always possible to set sleeve7 at its upper posit-ion, whatever the altitude, so that ports 9 areclosed and the mixture enriched.

It is thus possible, by means of this manual control to feed the engineeither with a weak mixture (economic cruising rating), or with a richone (climbing, maximum power in altitude, etc.)

The embodiment shown in Fig. 2 is of the type with altimetricaladjustment through decrease in pressure above the level of the fuel inthe float chamber M which supplies the jet l. The device is similar tothe previous one and the operation identical, but the adjustment isachieved by connecting the neck of the venturi [0a to the upper part ofthe chamber I4 through duct 9a, seat 3 controlled by needle 4 and ports9 controlled by sleeve 1.

Over the fuel in chamber 14, a pressure less than atmospheric anddetermined according to the altitude by the position of the altimetricaladjusting needle 4, is thus created.

The third embodiment shown in Fig. 3 is of the type with altimetricaladjustment by reducing the flow of gasoline, the adjusting needle 4operated by the pressure responsive box 5 actin on the gasoline flowsupplying the jet 1 from container l4 through ports 3 and 9 and duct l5.

On this needle is arranged the sliding sleeve 1 operable to cover oruncover one or more ports 9 connecting, through the inner cavity ofneedle 4, container I4 and duct l5 of the emulsifier. The device is suchthat these ports 9 are wholly or partly uncovered for high air inletpressures, while they are covered for low air inlet pressures owing tothe action of the pressure responsive box 5.

As above, it is further possible to arrange a manual control foroperation with either weak or rich mixtures.

The advantages of the invention are as follows:

1. Automatic regulation of the richness for high air inlet pressureswith a single atmospheric pressure responsive box, the action of whichis combined with that of sleeve 1 and ports 9 according to the apertureof the air throttle, enabling to obtain simultaneously the altimetricaladjustment and a richness varying according to the air inlet pressure.

2. Possibility to operate automatically with a very economicaladjustment (weak mixture).

3. Possibility to have the maximum engine power available at altitudesby the operation of the primer (rich mixture-ratio).

4. Possibility to increase the richness for high power ratings requiredfrom the engine (climbing for instance).

What I claim is:

1. In a carburetor for an aircraft engine without compressor having amovable air throttle and a mixing space, two valve devices arranged inparallel relationship to control independently from one another the fuelsupply to the mixing space, one of said valve devices being adapted toreduce the fuel supply in response to a decrease in atmospheric pressureand conversely, while the other valve device includes two valve membersarranged to move independently with respect to one another, one of saidmembers being adapted.

to reduce the fuel supply in response to a decrease in atmosphericpressure and conversely,. and means for connecting operatively theothermember to the throttle, said means being adapted to move said othermember towards its fuel sup-- ply increasing position when the throttleis open and conversely.

2. In a carburetor for an aircraft engine without compressor, having amovable air throttle and a mixing space, a regulating device for thefuel supply to said mixing space comprising a fuel supply controlpassageway, a stationary seat provided in said passageway, a movableneedle the outer surface of which is adapted to cooperate with said seatin order to vary the cross-section area of said passageway, meanssensitive to the atmospheric pressure operatively connected to saidneedle and adapted to move it with respect to said seat so as to reducethe fuel supply in response to a decrease in atmospheric pressure andconversely, said needle being provided with an internal cavity and withlateral ports adapted to connect said cavity respectively with the portsof said passageway located on each side of said seat so as t form asecond fuel supply control passageway arranged in parallel relationshipwith respect to the first-named passageway. a sleeve slidably mounted onsaid needle so as to control its ports on one side of said seat, andmeans mechanically connecting said sleeve to said movable air throttle,said means being adapted to move said sleeve with respect to thecorresponding needle ports towards the fuel supply increasing positionof said sleeve when the throttle is open and conversely.

3. In a carburetor for an aircraft engine without compressor, having amovable air throttle and a mixing space, an emulsifier the exit of whichis connected to said mixing space, an air passageway connected to theatmosphere and to the exit of said emulsifier, two valve devicesarranged in para1le1 relationship in said air passageway to controlindependently from one another the cross-section area of said airpassageway, one of said valve devices being adapted to increase thecross-section area of said air passageway in response to a decrease inatmospheric pressure and conversely, whil th other valve device includestwo valve members arranged to move independently with respect to oneanother, one of said members being adapted to increase the cross-sectionarea of said air passageway in response to a decrease in atmosphericpressure and conversely, and means for connecting operatively the othermember to the said throttle, said means being adapted to move said othermember towards its cross-section area reducing the position when thethrottle is open and conversely.

4. In a carburetor for an aircraft engine without compressor, having amovable air throttle and a mixing space, an emulsifier the exit of whichis connected to said mixing space, an air passageway connected to theatmosphere and to the exit of said emulsifier, a stationary seatprovided in said air passageway, a movable needle the outer surface ofwhich is adapted to cooperate with said seat in order to vary thecross-section area of said air passageway, means sensitive to theatmospheric pressure operatively connected to said needle and adapted tomove it with respect to said seat so as to increase the cross-sectionarea of said air passageway in response to a decrease in atmosphericpressure and conversely, said needle being provided with an internalcavity and with lateral ports adapted to connect said cavityrespectively with the ports of said passageway located on each side ofsaid seat so as to form a second air passageway arranged in parallelrelationship with respect to the firstnamed passageway, a sleeveslidably mounted on said needle so as to control its ports on one sideof said seat, and means mechanically connecting said sleeve to saidmovable air throttle, said means being adapted to move said sleeve withrespect to the corresponding needle ports towards the ports openingposition of said sleeve when the throttle is open and conversely.

ROGER H. TISSIER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,802,321 Mabee et a1. Apr. 21,1931 2,203,858 Booty June 11, 1940 2,212,101 Kratzer Aug. 20, 19402,216,677 Schuttler Oct. 1, 1940 2,291,048 Lichtenstein July 28, 1942FOREIGN PATENTS Number Country Date 109,099 Great Britain Aug. 31, 1917

